Orthogonal signal correction assisted multivariate regression approach for the estimation of uranium and acidity in PUREX process streams.

A direct UV-Visible absorbance spectrophotometric method was developed for the simultaneous determination of uranium and nitric acid concentration in the PUREX process samples. The simulated system consisted of uranium and nitric acid in concentration range corresponding to reprocessing of spent nuclear fuel discharged from nuclear reactor was prepared. The absorbance of these samples was measured in the range of 400-470 nm at a scan speed of 100 nm/s and resultant spectra were recorded. The changes in wavelength maxima of U(VI) absorption spectrum at different nitric acid concentration was utilized to determine the concentration of uranium and nitric acid in the sample by orthogonal signal correction assisted principal component regression. After the principle component regression the RMSEP for test data (Uranium: 3-21 g/L and acidity: 2-12 M) were 0.7 g/L and 0.4 M respectively. This method is superior to conventional method being followed for routine analysis of plant control samples in view of minimizing the generation of radioactive analytical waste consisting other corrosive reagents and reducing radiation exposure to operators during analysis. This method is amenable for online monitoring also.